package com.hmdp.service.impl;

import cn.hutool.core.lang.func.Func1;
import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.RedisConstants;
import com.hmdp.utils.RedisData;
import com.hmdp.utils.SystemConstants;
import jodd.util.StringUtil;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;
import java.time.LocalDateTime;
import java.util.*;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.function.Function;

import static com.hmdp.utils.RedisConstants.*;

/**
 * <p>
 * 服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {
    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Resource
    private CacheClient cacheClient;

    /**
     * 根据id查询商铺信息
     *
     * @param id
     * @return
     */
    @Override
    public Result queryById(Long id) {
        //缓存穿透 缓存空值
        //Shop shop = queryWithPassThrough(id);
        Shop shop = cacheClient.
                queryWithPassThrough(CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);

        //缓存击穿 互斥锁
        //Shop shop = queryWithMutex(id);

        //缓存击穿 逻辑过期
        //Shop shop = queryWithLogicalExpire(id);
        //Shop shop = cacheClient.
        //        queryWithLogicalExpire(CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);

        if (shop == null) {
            return Result.fail("店铺信息不存在");
        }
        //返回商铺信息
        return Result.ok(shop);
    }

    //独立线程
    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);

    /**
     * 缓存击穿 逻辑过期
     *
     * @param id
     * @return
     */
    public Shop queryWithLogicalExpire(Long id) {
        String key = CACHE_SHOP_KEY + id;
        //1.从redis中查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断缓存是否存在
        if (StrUtil.isBlank(shopJson)) {
            //不存在，直接返回空(说明其不是热点商品)
            return null;
        }
        //3.将redis数据反序列化为对象
        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
        LocalDateTime expireTime = redisData.getExpireTime();
        Shop shop = JSONUtil.toBean((JSONObject) redisData.getData(), Shop.class);
        //4.判断逻辑时间是否过期
        if (LocalDateTime.now().isBefore(expireTime)) {
            //如果未过期，直接返回
            return shop;
        }
        //如果已过期，需要缓存重建
        //5.缓存重建
        //5.1获取互斥锁
        String lockKey = LOCK_SHOP_KEY + id;
        boolean isLock = tryLock(lockKey);
        //5.2判断是否获取锁
        if (isLock) {
            //5.3获取到，开启独立线程，实现缓存重建
            CACHE_REBUILD_EXECUTOR.submit(() -> {
                try {
                    //重建缓存
                    saveShopHotRedis(id, CACHE_SHOP_TTL);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                } finally {
                    //释放锁
                    unlock(lockKey);
                }
            });

        }
        //5.4未获取到，直接返回过期数据
        return shop;
    }

    /**
     * 缓存击穿 互斥锁
     *
     * @param id
     * @return
     */
    public Shop queryWithMutex(Long id) {
        String key = CACHE_SHOP_KEY + id;
        //1.从redis中查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断缓存是否存在
        if (StrUtil.isNotBlank(shopJson)) {
            //存在，直接返回
            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
            return shop;
        }
        //3.判断是否为空值
        if (shopJson != null) {
            //为空值，返回一个错误信息（解决缓存穿透问题）
            return null;
        }
        //4.实现缓存重建
        //4.1 获取互斥锁
        String lockKey = LOCK_SHOP_KEY + id;
        Shop shop = null;
        try {
            boolean isLock = tryLock(lockKey);
            //4.2 判断是否获取成功
            if (!isLock) {
                //4.3 失败，则休眠并重试
                Thread.sleep(50);
                return queryWithMutex(id);
            }
            //4.4 成功，根据id查询数据库
            shop = getById(id);
            //5.判断数据库中是否存在
            if (shop == null) {
                //6.不存在，缓存空值（解决缓存穿透问题）
                stringRedisTemplate.opsForValue().set(key, "", CACHE_NULL_TTL, TimeUnit.MINUTES);
                return null;
            }
            //7.存在，将商铺信息存入redis缓存
            stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop), CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        } finally {
            //8.释放互斥锁
            unlock(lockKey);
        }
        //9.返回
        return shop;
    }

    /**
     * 缓存穿透 缓存空值
     *
     * @param id
     * @return
     */
    public Shop queryWithPassThrough(Long id) {
        String key = CACHE_SHOP_KEY + id;
        //1.从redis中查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断缓存是否存在
        if (StrUtil.isNotBlank(shopJson)) {
            //存在，直接返回
            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
            return null;
        }
        //3.判断是否为空值
        if (shopJson != null) {
            //为空值，返回一个错误信息（解决缓存穿透问题）
            return null;
        }
        //4.缓存中不存在，查询数据库
        Shop shop = getById(id);
        //5.判断数据库中是否存在
        if (shop == null) {
            //6.不存在，缓存空值（解决缓存穿透问题）
            stringRedisTemplate.opsForValue().set(key, "", CACHE_NULL_TTL, TimeUnit.MINUTES);
            return null;
        }
        //7.存在，将商铺信息存入redis缓存
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop), CACHE_SHOP_TTL, TimeUnit.MINUTES);
        return shop;
    }

    /**
     * 获取互斥锁
     *
     * @param key
     * @return
     */
    private boolean tryLock(String key) {
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10L, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }

    /**
     * 释放互斥锁
     *
     * @param key
     */
    private void unlock(String key) {
        stringRedisTemplate.delete(key);
    }

    /**
     * 存储含过期时间的店铺信息
     *
     * @param id
     * @param expireSeconds
     */
    public void saveShopHotRedis(Long id, Long expireSeconds) throws InterruptedException {
        //1.查询店铺
        Shop shop = getById(id);
        Thread.sleep(200);
        //2.封装过期时间
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        //3.存入redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id, JSONUtil.toJsonStr(redisData));
    }

    /**
     * 更新商铺信息
     *
     * @param shop
     * @return
     */
    @Override
    @Transactional
    public Result updateShop(Shop shop) {
        Long id = shop.getId();
        if (id == null) {
            return Result.fail("店铺id不能为空!");
        }
        //1.修改数据库信息
        updateById(shop);
        //2.删除缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY + id);
        return Result.ok();
    }

    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        //1.判断是否需要根据坐标查询
//        if (x == null || y == null) {
            // 不需要坐标查，按数据库查
            Page<Shop> page = query()
                    .eq("type_id", typeId)
                    .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            // 返回数据
            return Result.ok(page.getRecords());
//        }

        //2.计算分页参数
//        int from = (current - 1) * SystemConstants.DEFAULT_PAGE_SIZE;
//        int end = current * SystemConstants.DEFAULT_PAGE_SIZE;
//
//        //3.查询redis，按照距离排序、分页。结果：shopId，distance
//        String key = SHOP_GEO_KEY + typeId;
//        GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo()  //GEOSEARCH key BYLONLAT x y BYRADIUS 10 WITHDISTANCE
//                .search(
//                        key,
//                        GeoReference.fromCoordinate(x, y),
//                        new Distance(5000),
//                        RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeDistance().limit(end)
//                );
//        //4.解析出id
//        if (results == null) {
//            return Result.ok(Collections.emptyList());
//        }
//        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> list = results.getContent();
//        if (list.size() <= from) {
//            //没有下一页，结束
//            return Result.ok(Collections.emptyList());
//        }
//        //4.1截取从 from~end 部分
//        List<Long> ids = new ArrayList<>(list.size());
//        Map<String, Distance> distanceMap = new HashMap<>(list.size());
//        list.stream().skip(from).forEach(result -> {
//            //4.2获取店铺id
//            String shopIdStr = result.getContent().getName();
//            ids.add(Long.valueOf(shopIdStr));
//            //4.3获取距离
//            Distance distance = result.getDistance();
//            distanceMap.put(shopIdStr, distance);
//        });
//        //5.根据id查询Shop
//        String idStr = StringUtil.join(ids, ",");
//        List<Shop> shops = query().in("id", ids).last("order by field(id," + idStr + ")").list();
//        for (Shop shop : shops) {
//            shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
//        }
//        //6.返回
//        return Result.ok(shops);
    }

}
